* Record numbers of migrants arrive in Croatia and Germany
* EU calls emergency summit, Croatia overwhelmed by influx
* More refugees are heading for Europe

Ban Ki-moon was 'shocked' at the 'unacceptable' treatment of asylum seekers.A baby cries as migrants board a bus in Tovarnik, Croatia, September 17, 2015. REUTERS/Antonio BronicA Croatian policeman holds a crying baby as he stands among migrants waiting to board a bus in Tovarnik, Croatia, September 17, 2015. REUTERS/Antonio BronicA migrant and a policeman run during a stampede to board a bus in Tovarnik, Croatia September 17, 2015. REUTERS/Antonio

AMID chaotic scenes at its border with Serbia, Croatia said today it could not cope with a flood of migrants seeking a new route into the EU after Hungary kept them out by erecting a fence and using tear gas and water cannon against them.

AMID chaotic scenes at its border with Serbia, Croatia said today it could not cope with a flood of migrants seeking a new route into the EU after Hungary kept them out by erecting a fence and using tear gas and water cannon against them.

The European Union's newest member state said it may try to stop taking in migrants, just as the 28-nation bloc announced it leaders would hold an emergency summit on Sept. 23 to try to resolve the migration crisis, which has deeply divided it.

Hungarian riot police charge migrants at the border crossing with Serbia in Roszke, Hungary September 16, 2015. Reuters/Karnok CsabaA migrant pushes a cart with children inside as they pass burning remains of the clashes earlier today at the border with Hungary near the village of Horgos, Serbia, September 16, 2015. Reuters/Stoyan NenovHungarian riot police hold a migrant at the border crossing with Serbia in Roszke, Hungary September 16, 2015. Reuters/Marko DjuricaAn injured migrant carries a child during clashes with Hungarian riot police at the border crossing with Serbia in Roszke, Hungary September 16, 2015. Reuters/Karnok Csaba

More than 7,300 people entered Croatia from Serbia in the 24 hours after Wednesday's clashes between Hungarian riot police and stone-throwing refugees at its Balkan neighbour's frontier.

At the eastern border town of Tovarnik, Croatian riot police struggled to keep crowds of men, women and children back from rail tracks after long queues formed in baking heat for buses bound for reception centres elsewhere in Croatia.

Police were also deployed in a suburb of the capital Zagreb, taking up positions around a hotel housing hundreds of migrants, some of them on balconies shouting "Freedom! Freedom!". Others threw rolls of toilet paper from the balconies and windows.

"Croatia will not be able to receive more people," Interior Minister Ranko Ostojic told reporters in Tovarnik.

"When we said corridors are prepared (for migrants), we meant a corridor from Tovarnik to Zagreb," he added, suggesting Croatia would not simply let migrants head north to Slovenia, which is part of the EU's Schengen zone of border-free travel.

The flood of migrants into Croatia has accelerated since Hungary sealed its southern, external EU frontier with Serbia on Tuesday, to keep out the asylum seekers and refugees, many of whom hope eventually to reach wealthy Germany.

"I just want to go," Syrian Kamal Al'hak said in Tovarnik, among people sitting or lying by the tracks trying to shade themselves from the sun. "I may return to Syria, but only in a few years. It's too dangerous there now."

The EU is split over how to cope with the influx of people mostly fleeing war and poverty in Syria, Iraq, Afghanistan and Pakistan.

European Council President Donald Tusk summoned EU leaders to an extraordinary summit next Wednesday to discuss migration and a proposed scheme to distribute 120,000 asylum seekers across the bloc.

The bloc's interior ministers failed on Monday to agree on a mandatory quota system designed to spread the burden of this year's huge influx of migrants and German Chancellor Angela Merkel, leader of the EU's most powerful member state, had called for an emergency summit.

EU commissioner for migration Dimitris Avromopoulos rebuked Hungary over its actions, telling a joint news conference with Hungary's foreign and interior ministers that most of those arriving in Europe were Syrians "in need of our help".

"There is no wall you would not climb, no sea you would not cross if you are fleeing violence and terror," he said, describing barriers of the kind Hungary has erected as temporary solutions that only diverted migrants, increasing tensions.

"It is bizarre and shocking how some members of international political life and the international press interpreted yesterday's events," he said. "All these people will be responsible if these events are repeated today, tomorrow or the day after tomorrow."

In Brussels, Johannes Hahn, the EU's commissioner in charge of enlargement, urged member states to stay calm and fight the crisis together.

"The Western Balkans must not become a parking lot for refugees. That would be a grave geostrategic mistake. Cool heads on all sides are all needed now, not harsh rhetoric," he said.

Undeterred by the problems faces by migrants at the gates of Europe, more have been arriving at the Greek port of Piraeus from Lesbos island, a route taken by many refugees.

Others are still waiting outside Europe, despite the hazardous Journey which has cost some refugees their lives.

"It would be very dangerous, but if you make it, the reward is great, the whole world will open up for you," Yousef Hariri, a refugee from Deraa in Syria, said at a refugee camp in Jordan.

German police said the number of refugees arriving in Germany more than doubled on Wednesday to 7,266.

The head of Germany's Office for Migration and Refugees quit for personal reasons after being criticised for slow processing of applications from a record number of asylum seekers.

Hungarian Prime Minister Victor Orban, who has blamed Berlin for stoking the wave of migrants entering his country after Merkel rolled out the welcome mat for Syrian refugees, said Muslims would end up outnumbering Christians in Europe if the policy continued.

"I am speaking about culture and the everyday principles of life, such as sexual habits, freedom of expression, equality between men and woman and all those kind of values which I call Christianity," Orban said in an interview published in several European newspapers including The Times.

The UN human rights chief, Zeid Ra'ad al Hussein, in turn hit back by denouncing "callous, xenophobic and anti-Muslim views that appear to lie at the heart of current Hungarian government policy".

The European Parliament endorsed on Thursday the Commission proposal for the relocation of 120,000 migrants from Italy, Greece and Hungary, opposed by four central European states including Hungary itself.

Two German ministers have spoken of cutting European funds to central European member states that refuse to take their allotted share of refugees.

The future of border-free travel in the Schengen zone of 26 continental European states has been cast in doubt by the uncoordinated national actions to revive frontier checks.

"Europe was created to knock down walls, not to build them," Italian Prime Minister Matteo Renzi said after talks with Luxembourg's premier.

Croatian Prime Minister Zoran Milanovic said his country cannot hold migrants who wish to move on toward Western Europe, claiming "our resources are limited".

He added: "We will not and cannot keep them in Croatia and no one will make us do that."